the coal handbook: towards cleaner production || coal use in iron and steel metallurgy

© Woodhead Publishing Limited, 2013

267

12 Coal use in iron and steel metallurgy

A. BABICH and D. SENK, RWTH Aachen University, Germany

DOI : 10.1533/9781782421177.3.267

Abstract: This chapter discusses the role of coal in iron and steel metallurgy. The chapter fi rst gives information about routes for steel manufacture, current levels of steel production and forecasts for the future. It then discusses the use of coal in different metallurgical processes with emphasis on various ironmaking technologies as the most energy consuming step of the process chain. Alternatives to coal like biomass, hydrogen or waste plastics are discussed from the point of view of CO 2 reduction.

Key words: cokemaking, blast furnace, direct and smelting reduction, electric steelmaking, ladle metallurgy, continuous casting.

12.1 Introduction

Steel is commonly used in modern society and is probably the most impor-

tant construction material of today (Fig. 12.1). This chapter deals with coal

use and ways for increasing its effi ciency in ironmaking, steelmaking, second-

ary or ladle metallurgy and continuous casting by different steel production

routes.

More attention is paid to ironmaking as the most energy consuming seg-

ment of the process chain. For example, blast furnace ironmaking including

sintering and coking plants consumes about 65–75% of the entire energy

at an integrated steelworks (ca. 11–12 GJ/t hot metal) (Babich, 2009). Both

direct and indirect coal use, e.g. in the form of coke, is presented. Use of coal

and coke breeze for sintering is out of the scope of this contribution.

Furthermore, alternatives to coal materials and energy sources such as

biomass or waste plastics are discussed, which are of great importance in the

course of efforts to recycle secondary sources and to mitigate carbon diox-

ide emissions due to the global climate change challenge.

12.1.1 Steel production routes and trends

There are four main steel production routes in modern ferrous metal-

lurgy: blast furnace-basic oxygen converter (BF-BOF), smelting reduction

268 The coal handbook


– converter (SR-BOF), direct reduction – electric arc furnace (DR-EAF),

and scrap-electric arc furnace (Fig. 12.2) (Steel Institute VDEh, 2008). In

the fi rst route, hot metal is produced in the BF which is then refi ned in

the BOF to produce liquid crude steel. In the second route, liquid metal is

Steel

595

1412

AluminiumInt. Aliuminium

Institute

22 56,4 0,24 0,61 27

265

MagnesiumInt. Magnesium

Association

PlasticsPlastics Europe Market

Research Group

12.1 World production 1970/2010 (million t/a). ( Source : Adapted from

Stahl-Online, 2011.)

Blast furnace

Lump oreLump oreSinter

Coal

Coke

Pre-reduction

Meltergasifier

Pellets

Pellets

Pellets

Coal DR

DRI

Scrap

Scrap

EAF(electric arc furnace)

Naturalgas

Rotarykiln

Fluidisedbed

ShaftFurnace

BF

Coal,

Coal

Naturalgas, oil

Directreduction

Fine ore

Scrap

Oil, gas

O2

O2

O2

Air, O2

Hot metalscrap

Hot metalscrap

BOF (converter) BOF

Smeltingreduction

12.2 Steelmaking process routes. ( Source: Adapted from Steel Institute

VDEh, 2008.)

Coal use in iron and steel metallurgy 269


produced in the melter-gasifi er without cokemaking and sintering, which

is also refi ned in the converter to produce liquid crude steel. In the third

route, sponge iron instead of hot metal is produced and then this directly

reduced iron is melted in the EAF. In the fourth route, only scrap is used

as solid metallic input to produce liquid crude steel in the EAF.

The BF has existed for over 700 years and remains the main aggregate

for reduction of iron ores. It has demonstrated fl exibility and adaptability

to changing conditions and today produces up to 10 000–13 000 tons of hot

metal a day. Besides coke and auxiliary fossil reducing agents such as coal,

oil and natural gas, further renewable and secondary sources can be used

to perform both chemical reduction work and necessary heat generation.

The liquid products – hot metal and slag – can be effectively separated from

each other. Pre-treatment of the hot metal enables reduction of the levels of

tramp elements prior to the refi ning process (Steel Institute VDEh, 2008).

The direct reduction processes in combination with the melting of directly

reduced iron to produce steel in the EAF offer an alternative to the BF-BOF

route. The basis of the direct reduction process is that solid sponge iron is

produced by removing oxygen from the ore in a shaft furnace, rotary kiln

furnace or fl uidised bed. Sponge iron can be produced in the form of Direct

Reduced Iron (DRI), Hot Briquetted Iron (HBI) and Cold Briquetted Iron

(CBI); also Low Reduced Iron (LRI), which is pre-reduced iron ore with a

reduction and metallisation degree lower than that for common DRI, can

be produced. The direct reduction processes can be divided into gas reduc-

tion and coal reduction processes depending on the type of reducing agent

used (see Section 12.5). DRI and HBI are predominantly processed in the

EAF, and predominantly for the production of steel grades of long prod-

ucts. Compared to scrap, the advantage of DRI/HBI is low content of trace

elements; however, the disadvantage is higher cost (Steel Institute VDEh,

2008). Furthermore, DRI/LRI can also be applied as pre-reduced material

for the BF.

The smelting reduction processes are characterised by the production of

hot metal from iron ores without an agglomeration step and almost without

coke. Classifi cation and examples of SR processes are given in Section 12.7.

The advantages of this technology are low demand on coke and increased

energy utilisation effi ciency as a result of post-combustion of CO (Steel

Institute VDEh, 2008).

In the year 2011, 1490.1 million ton (Mt) of crude steel, 1082.7 Mt of blast

furnace hot metal and 63.5 Mt of DRI were produced worldwide (World

Steel Association, 2013). The ratios of oxygen steel and electric steel were

69.6% and 29.2%, respectively; the worldwide metallic charge was 1690 Mt,

and the major part of it was hot metal from blast furnace (64.7%), the rest

was mainly steel scrap (30.6%); the share of DRI/HBI and hot metal from

smelting reduction (Corex ® /Finex ® ) was 4.3% and 0.4%, respectively (Peters



and Schmoele, 2012). According to the analysis, an increase in world steel

production is expected until 2020–2025 (Harada and Tanaka, 2011).

12.1.2 The role of coal in the steel industry

Carbon is a major reducing agent and heat source to convert iron ores to

iron and steel. The required amount of carbon is determined by thermody-

namics and chemical kinetics. Carbon in the steel industry is used mainly in

the form of coal and the product of its thermal treatment – coke – but can

also be used in the forms of biomass, hydrocarbons (natural gas) and C-H

compounds like oil or plastics.

Contrary to the almost pure iron of meteoric origin, manufactured iron

(pig iron or hot metal) and steel are ferrous alloys of iron with carbon and

further impurities (Fig. 12.3). Carbon lowers the melting point of iron from

1538 ° C in pure iron to 1147 ° C in the eutectic with 4.3% C. Carbon content

in steel is up to 2.14 % that corresponds to maximum dissolubility of carbon

in γ -iron (usually C-content in steel does not exceed 1.5%). Carbon content

in hot metal makes up more than 2.5% (typically 4–5%); ferromanganese

may contain up to 6.0–6.5% C. Alloys with carbon content from 2% to 2.5%

have no technical application. The properties of pig iron and steel depend

signifi cantly on their carbon content.

1600

1400

1200

1000

800

600

4000

(Fe) Composition (wt% C)

1538°C1493°C

1394°C

1147°C

727°C

4.30

912°C

Tem

pera

ture

(°C

)

0.760.022

2.14γ, Austenite

α, Ferrite α + Fe3C

αγ

γ + L

L

γ + Fe3C

Cementite (Fe3C)

1 2 3 4 5 6 6.7

+

δ

12.3 Iron-Carbon Phase Diagram (University of Tennessee, 2011).



12.1.3 Challenges regarding CO 2 emissions

Reducing CO 2 emissions is the biggest challenge facing the steel industry.

The CO 2 emission from the BF-BOF route is approximately 2 tons per

ton of crude steel (Riley et al ., 2010); for the DR-EAF route this value is

33% lower (using the Midrex-EAF process (Ameling et al ., 2011). Non-

carbon metallurgy based on hydrogen, plasma or electricity is still far

away from industrial application. In the short and medium terms, CO 2

emissions should be mitigated by signifi cant increase in carbon effi ciency,

using renewable energy sources like biomass or products of their process-

ing – charcoals, semi-charcoals or torrefi ed materials, and development

and introduction of CCS technologies for blast furnace ironmaking, direct

and smelting reduction processes as well as processing of CO 2 into chem-

ical products.

12.2 Cokemaking

The cokemaking process is defi ned as the heating of natural, organic, mostly

solid materials in an oxygen defi cient atmosphere in order to concentrate

the carbon. Here that term is used for carbonisation of pit coal to high

temperatures (about 1100 ° C) to produce metallurgical coke (Babich et al ., 2008). The chemical composition and the physical properties of coke are

infl uenced by the coal used and coking conditions. Blends of coals with dif-

ferent plastic properties are typically used.

Two main types of coke are produced (Coaltech, 2011):

1. Metallurgical coke is produced in coke ovens and is mainly consumed

in ironmaking blast furnaces but also in blast and electric furnaces for

ferroalloy production as well as for reduction of phosphates, sulphates,

chlorides, and carbonates.

2. Foundry coke is produced in beehive or non-recovery coke ovens and is

used at foundries to melt iron as well as copper, lead, tin and zinc alloys

in cupolas.

The third type of coke is domestic coke or semi-coke.

This contribution deals with metallurgical blast furnace coke.

12.2.1 Conventional coke production

Horizontal ovens (or chambers) heated from the wall side are mostly used

for coke making. From the wall the front of highest temperature proceeds

through the coal blend and initialises the coking process.



The reactions taking place in the chamber depend on the temperature

(the letters refer to Fig. 12.4) (Babich et al ., 2008):

e <100 ° C The coal blend is dried (hydroscopic water is evaporated).

d 100–350 ° C Absorbed gases like nitrogen, methane and carbon dioxide

are extracted and coal is dehydrated. Above 250 ° C the fi rst products of

thermal decomposition appear.

c 350–480 ° C The coal loses its strength and its plastic properties appear;

the coal swells which leads to the porous structure of the fi nal product.

Bitumen is evaporated.

b 480–600 ° C Semi-coke is formed. The crack distribution is determined

due to the shrinkage.

a 600–1100 ° C Final coke is formed.

The chamber has typically a width in the range of 450–600 mm, height of

4–8 m, and length of 12–18 m. It corresponds to about 40–70 m 3 of useful

volume. The typical chamber productivity varies in the range from 6200 to

17 000 t/year or from 25 to 36 kg/m 3 /h (Nashan et al ., 2000). A coke battery

(Fig. 12.5) is formed usually from 50–70 coke chambers.

Exemplary characteristics of the modern coking plant at the Duisburg

Schwelgern (KBS Duisburg) with 140 ovens in two batteries are presented

in Table 12.1.

0

1200After 4 h After 8 h After 13 h After 20 h

a b c d e a bc a abcde

1000800600400200

Tem

pera

ture

(°C

)

0220 440 0 220

Chamber width (mm)

440 0 220 440 0 220 440

f f f f

12.4 Processes during coking and temperature change along the

chamber width. ( Source: Adapted from RuhrkohlenHandbuch, 1984.)



After a coking time of about 20 h red-hot coke is pushed via the guide car into

the quenching car and transported to the coke quenching (dry or wet) where the

coke is cooled down and stabilised. The heated-up cooling gas can be recovered.

12.5 Photo of coke battery (Babich et al ., 2008).

Table 12.1 Main data of coking plant at the Duisburg Schwelgern

Number of ovens 2 × 70

Chamber dimensions, length × height ×

width, m

20.8 × 8.3 × 0.59

Effective chamber volume, m 3 93

Pushed ovens per day 135

Charging holes 560

Coking time, h 24.9

Average heating fl ue temperature, ° C <1325

Coke capacity, million t/a 2.64

Gas treatment plant capacity, Nm 3 /h 155 000

Source : Adapted from Liszio, 2003; Neuwirth and Schuster, 2003;

Siebelhoff and Taylor, 2004.



The coke oven gas (410–560 Nm 3 /t of coke depending on the volatile mat-

ter) content in the coal charge (Bender et al ., 2008) is cleaned from tar, ben-

zol and sulphur. The refi ned coke oven gas (55–65% H 2 , 24–28% CH 4 , 6–8%

CO, 2–4% CO 2 , 2–3% C m H n , the rest: O 2 , N 2 ; low calorifi c value 16.5–18.5

MJ/Nm 3 ) can be used for the heating of coke ovens, blast furnace hot stoves,

for DRI production, for injection into the BF, for power generation and for

further purposes.

12.2.2 Alternative cokemaking technologies

Several cokemaking technologies, alternative to the conventional multi-

chamber or slot coking system, have been developed in the face of the chal-

lenges of keeping coke high quality while increasing the share of low-caking

coals in the blend and increased requirements on environmental protection.

Examples of such new technologies are:

− non-recovery system,

− heat-recovery system,

− single chamber system,

− SCOPE21 process.

Here only the non- and heat-recovery coking systems are presented.

The non-recovery system is derived from the old beehive ovens of the nine-

teenth century. Beehive ovens operate under negative pressure, eliminating

by-products by incinerating the off-gases. In non-recovery coking plants the

coal is carbonised in large oven chambers. The carbonisation process takes

place from the top by radiant heat transfer and from the bottom by conduc-

tion of heat through the sole fl oor. Primary air for combustion is introduced

into the oven chamber through several ports located above the charge level

in both pusher and coke side doors of the oven. Partially combusted gases

exit the top chamber through vertical ducts in the side walls (downcomers)

and enter the sole fl ue, thereby heating the sole of the oven. Combusted

gases collect in a common tunnel and exit via a stack which creates a natu-

ral draft in the oven. In non-recovery cokemaking the by-products are not

recovered, i.e. the waste gas is emitted to the atmosphere without utilisation

(Valia, 2011). In heat recovery ovens, the complete gas generated from coal

carbonisation is combusted directly in the oven space due to the operation

under suction, thus creating heat needed for carbonisation (Hoffman et al ., 2001). The waste gas exits into a waste heat recovery boiler which converts

the excess heat into steam for power generation (Valia, 2011).

In a heat recovery plant, the coal blend is charged into the ovens where

the coking process starts. The oven design is shown in Fig. 12.6 (Kalinin

and Campos, 2010). Immediately after the charging, the coal absorbs heat



from the refractory material. The volatile matters start to rise from the coal

bed and are completely combusted inside the oven, transferring the heat

back to the refractory material and preparing the oven for the next cycle.

At the oven crown above the coal bed, partial combustion of the volatile

matters takes place. The partially combusted gases are led into the heating

fl ue system under the oven sole where more air is introduced to complete

combustion (Arendt et al ., 2006; Kalinin and Campos, 2010). This enables

carbonisation from the top to the bottom of the bed at equal rates which

results in symmetrical coking fronts (Kalinin and Campos, 2010).

The coal charge in the heat recovery oven has dimensions of approx.

15 × 4 × 1 m (length × width × thickness of layer) (Arendt et al ., 2006).

SunCoke Energy operates fi ve plants in the USA and in Brazil with a capac-

ity equal to or higher than 40.3 tons of coal per oven and a coking time of

about 48 h (Kalinin and Campos, 2010). The heat recovery coking plant of

ThyssenKrupp CSA in Brazil with an annual capacity of 2 Mt has 432 cham-

bers in 3 batteries; coal charge is 49 tons and coking time 63 h (Eichelkraut,

2011).

A new generation of heat recovery ovens is operated by applying com-

pacting of coal before charging (Wright et al ., 2005). This technology is

known from the coal stamping used for slot ovens.

The form coking method consisting of briquetting of low-grade and low-

cost carbonaceous feed-stocks and then carbonising the briquettes contrary

to carbonising the coal blend is used in conventional slot ovens (Smoot

et al ., 2007).

Hot gas deliveryGas flowcontrollersfor each oven

Flue gas flowsto the tunnel

Door holedampers forprimary air

Sole flue dampers forsecondary air addition

Completely oxidised gasis sent to the oven walls

Combustionfas flows fromthe bottom tothe centre

Coal layer absorbs heat from therefractory and starts gas combustion

Partially combusted gas isdrawn through downcomers5

5

6

5

21

44 2

3

4

12.6 Scheme of the heat recovery coke ovens. ( Source: Adapted from

Kalinin and Campos, 2010.)



12.2.3 Additives to coal blends

The use of renewable charcoal and waste plastics is the option for reduc-

ing CO 2 emissions. The feasibility of using charcoal from various biomass

types and plastics from municipal wastes of various compositions in coal

blends for the production of blast furnace coke was investigated, focusing

on the effects of these materials on coal thermal behaviour, coking pressure

and quality of cokes produced in semi-pilot and pilot movable wall ovens

(Hanrot et al ., 2009).

The use of charcoal in the coal blend has a double advantage: the benefi t

of a CO 2 neutral source of carbon, and enhanced coke reactivity in order

to lower the reserve zone temperature of the blast furnace. With a charcoal

addition of 3 wt. % in a fl uid enough blend and by gravity charging, all coke

properties kept a correct level, but the gasifi cation temperature was reduced

by 100 ° C (Hanrot et al ., 2009).

In relation to plastic wastes, the effect of substitution of 2 wt. % of coal

in coal blends with different wastes was studied. The relative proportion

of polyolefi ns to other types of plastics in the waste is a critical factor in

order to maintain or improve the quality of the coke produced (Hanrot

et al ., 2009).

12.2.4 Coal for metallurgical coke production and coke properties

The rank and type of coal impact the coke strength while coal chemistry

determines largely the coke chemistry. In general, bituminous coals are used

for blending to produce BF coke of suitable quality at acceptable costs. The

most important coking properties of coal which infl uence the formation of

metallurgical coke are caking capacity, plasticity and swelling.

The following chemical, physico-chemical, physical and mechanical

characteristics of coke are of great importance for BF ironmaking (Babich

et al ., 2008):

proximate and ultimate analyses; •

break, pressure, abrasion; •

cold, hot and micro strength; •

size distribution; •

density and porosity; •

crack size and distribution; •

heat conductivity; •

calorifi c value; •

reactivity. •



Ultimate analysis (analysis of organic mass, wt. %), about: C = 96.5–97.5,

H = 0.2–0.8, O = 0.2–0.4, N = 0.7–1.3, S = 0.5–1.2.

Proximate analysis (for dry mass of coke): ash (A, typically 8–11%), vola-

tile matter (VM, about 1%) and sometimes sulphur (S, typically 0.5–1.0%).

Moisture (W, about 0.3–0.7% by dry quenching and 3–6% by wet quench-

ing) is given above 100%.

Fixed carbon: C fi x = 100 − (VM + A + S) or C fi x = 100 − (VM + A).

Coke ash consists mostly of acidic compounds: 50–75% of SiO 2 + Al 2 O 3 ,

ratio SiO 2 /Al 2 O 3 = 1.5–2.0; iron oxides = 10–20%; the rest: CaO, MgO, SO 2 ,

P 2 O 5 , Mn 3 O 4 , alkalis.

Reactivity characterises the velocity of generation of reducing gas accord-

ing to the reaction C + CO 2 = 2CO.

NSC test determines the C oke R eactivity I ndex (CRI) which is expressed

by the mass loss (%) of the specimen ( d = 20 mm, τ = 120 min, t = 1100 ± 5 ° C,

CO 2 = 5 l/min) (American Society for Testing and Materials, 1993).

Cold strength

MICUM test: drum indexes M 40 , M 10 : grain sizes of +40 mm (breakage) and

− 10 mm (abrasion) in % (drum: 1 × 1 m, 100 revolutions, 25 rev.min − 1 ) (Jones

and Kruse, 1982).

IRSID test: drum indexes I 40 , I 10 : grain sizes of +40 and − 10 mm in %

(drum: 1 × 1 m, 500 revolutions, 25 rev.min − 1 ) (Jones and Kruse, 1982).

ASTM test: grain sizes of +1 ″ (25 mm) and – ¼″ (6 mm) in % (drum:

0.46 × 0.91 m, 1400 revolutions, 24 rev.min − 1 ) (Jones and Kruse, 1982).

Hot strength

NSC test determines the C oke S trength after R eaction (CSR). The CSR

value is measured in one test procedure with CRI under gasifi cation of the

coke sample with carbon dioxide and expressed by the grain size portion

(in %) + 10 mm after 600 revolutions at 20 rev.min − 1 (American Society for

Testing and Materials, 1993; Men é ndez et al ., 1999).

Grain size (preferably 40–80 mm) should be higher for large blast furnaces.

Porosity of coke determines its specifi c inner surface (about 50%).

Bulk density depends on coke grain size, porosity, etc. ρ ≈ 430–500 kg/m 3 .

Standard characteristics of coke quality and test methods seem to be insuf-

fi cient to simulate changing conditions in a modern BF, described in the

next section (low coke rate, high pulverised coal injection rate, use of other

injectants). They provide limited assessment of coke properties under lim-

ited reacting conditions. There are numerous developments in this area which



could supplement the standard ones, e.g.: Global Coke Quality Index (Bonte

et al ., 2005), Deadman Cleanliness Index (DCI) (Nightingale et al ., 2002), coke

dissolution investigation (Gudenau et al ., 1990), coke texture characteristics

gained from optical refl ectance investigation in polarised light (Ollig, 1995),

investigation of coke behaviour under simulated changing BF conditions

using a Tammann furnace experimental set (Babich et al ., 2006; Babich et al ., 2009), optical particle analyser to measure the shape of the coke particles and

grain size distribution of blast furnace coke (Peters et al ., 2011).

12.3 Blast furnace ironmaking

Carbon use in a blast furnace in the form of both coke and auxiliary reduc-

ing agents is discussed in this section.

12.3.1 Coke use and quality

Coke is virtually the universal BF energy source. Use of auxiliary sources is

discussed in Section 12.3.2.

Coke fulfi ls three primary functions in the BF (Babich et al ., 2008):

it supplies heat; •

it acts as reducing agent; •

it supports the burden. •

Furthermore coke is a carbonising agent and dust fi lter.

The carbon of the coke and of the auxiliary reducing agents supplies the

major part, approximately 80%, of the heat required for the process (Babich

et al ., 2008). Heat is required for the endothermic reactions, preheating and

melting of the charge and heating of liquid products.

Carbon and oxygen react to carbon monoxide either directly (2C + O 2

= 2CO) or at high temperatures (above 900–1000 ° C) by means of the

Boudouard reaction (C + O 2 = CO 2 and then CO 2 + C = 2CO). The car-

bon monoxide (and also the hydrogen) acts as reducing media . Below 900–

1000 ° C iron oxides are reduced indirectly: Fe n O m + mCO = nFe + mCO 2 .

This process is slightly exothermic. At temperatures above 900–1000 ° C

direct reduction starts: Fe n O m + mC = nFe + mCO. Direct reduction is an

endothermic process and consumes heat.

Coke also maintains burden permeability . First liquid phases appear in the

cohesive zone at temperatures between 900 ° C and 1350 ° C (Gudenau et al ., 1998). Reduced iron and slag drop through the supporting checker-work of

glowing, solid coke. Coke keeps its solid form until the raceway level.

Due to carbonisation of iron the melting point decreases (see Section

12.1.2); this makes tapping at lower temperatures possible.



Dust in the form of char and soot, which might be generated in the hearth

while injecting the high rate of auxiliary reducing agents, is transported upwards

by the gas stream. They decrease gas permeability and increase apparent vis-

cosity of liquid phases. These negative phenomena are diminished when char

and soot cover coke pieces and react later (Gudenau et al ., 1998).

Figure 12.7 illustrates the effect of coke quality on the BF operation.

Quality requirements for coke can be derived from the functions in the

BF. The requirements of coke characteristics increase considerably with the

growth of the volume (especially height) of blast furnaces and with the drop

in the coke rate. In Table 12.2, requirements of coke properties in Europe

are given.

Principal factors causing coke degradation in the blast furnace are shown

schematically in Fig. 12.8.

Table 12.3 gives an overview of coke degradation mechanisms and corre-

sponding requirements on it related to coke functions in different zones.

Goodcoke

Badcoke

Top gastemperature

100

Tem

pera

ture

(°C

)

Lumpy zone

Deadman

Tuyer

Taphole

200400800

Increase ofdust

Impact onpermeability

Cohesive zone

Increase of heatload on the wall

Heat imbalanceand instability

Concentrated streamof molten material

Increase of finecoke particles

Raceway

Compactcoke zone

12.7 Infl uence of coke quality on blast furnace conditions (Gudenau

et al ., 1998).



12.3.2 Injection of coal and further auxiliary reducing agents

Decreasing the specifi c energy consumption rate has been a priority through-

out the entire history of the blast furnace. Operating improvements have been

remarkable over the years. Figure 12.9 demonstrates an example of the devel-

opment of the structure and rate of reducing agents in German blast furnaces.

Injection of auxiliary reducing agents as oil, natural gas and mainly pulverised

coal contributed in the past three decades largely to the drop in coke rate.

The BF technology with pulverised coal injection (PCI) is nowadays

widely spread around the globe. PCI rate of 200 kg/tHM and more is rea-

lised while the coke rate is less than 300 kg/tHM. Table 12.4 demonstrates

achieved reducing agent rate at some best performing BFs in Europe.

About 60% of BFs in EU-15 operate with PCI (the average rate in

2008 was 124 kg/t HM (Peters and Luengen, 2009), in 2009 – 103 kg/tHM)

(Luengen et al ., 2011a). In Japan all BFs operate using PCI; the majority of

BFs in China, many BFs in the USA and in some further regions use this

technology as well (the average injection rate in China was 147 kg/tHM in

2009 (Sha and Cao, 2011).

Babich et al . (2008) have reviewed coal properties and equipment for its

injection. In Table 12.5 the criteria for PCI coal selection at Ispat Inland,

USA, are given as an example.

When pulverised coal (PC) is injected via the tuyeres, carbon reacts with

oxygen of the blast and generates CO 2 , which reacts with burning hot coke

Table 12.2 Requirements of blast furnace coke

properties in Europe

Chemical properties (wt %)

Ash

Sulphur

Phosphorus

Alkalis

Moisture

<9.0

<0.7

<0.025

<0.2

<5.0

Physical properties

CSR, % >10 mm

CRI, %

I 40 , % >40 mm

I 10 , % <10 mm

>65

<23

>57

<18

Size fraction

>100 mm, %

>80 mm, %

<40 mm, %

<10 mm, %

0

<10

<18

<3

Source : Arendt et al ., 2006.



and transforms to carbon monoxide. A crucial problem is related mainly to

PC conversion (particularly at high injection rates) because its residence

time within the tuyere and the raceway makes up only hundredths of a sec-

ond. Unburnt coal particles may affect negatively gas permeability in the

furnace shaft, slag viscosity, coke characteristics, and fi nally, coke consump-

tion and furnace productivity. A number of measures for intensifying the PC

conversion in the raceway have been developed and summarised by Babich

et al . (2008); here they are only listed:

enriching the blast with process oxygen; •

local oxygen supply; •

using coal blends and mixtures of coal with non-combustible •

substances;

using chemical and physical phenomena; •

optimising the coal grinding. •

Bell

Coke

Stockline

900

950

1000

12001400

1400–1500

1500–16001600

>1600

15001600

>1600Tuyere

[1] Shattering

[2] Abrasion

[3] Solution loss reaction(C + CO2 → 2CO)

at chemical-control andpore diffusion-control region

[4] Alkaline attack

[5] High temperature attack

[6] Breakage by highspeed hot blast

0

678 900

1100

13001800

>1800

9101112131415161718192021222324

Dis

tanc

e fr

om th

e st

ockl

ie

12.8 Factors affecting the coke degradation in the blast furnace

(Matsubara et al ., 1983).



Furthermore, a part of injected PC which is not gasifi ed by the oxygen of

the blast can be utilised by reactions of secondary gasifi cation like reactions

with oxides in slag or with carbon dioxide in the shaft. In this context, char

generation and its behaviour in the blast furnace are of great importance

(Kruse et al ., 2003; Sahajwalla and Gupta, 2005).

Table 12.3 Coke functions, degradation mechanisms and requirements

BF zone Function of coke Coke degradation

mechanism

Coke requirements

Charging zone – Impact stress

– Abrasion

– Size distribution

– Resistance to

breakage

– Abrasion

resistance

Granular zone – Gas permeability – Alkali

Deposition

– Mechanical

stress

– Abrasion

– Size and

stability

– Mechanical

strength

– Abrasion

resistance

Cohesive zone – Burden support

– Gas permeability

– Iron and slag

drainage

– Gasifi cation of

CO 2

– Abrasion

– Size

distribution

– Low reactivity

to CO 2

– High strength

after abrasion

Active zone – Burden support

– Gas permeability

– Iron and slag

drainage

– Gasifi cation

by CO 2

– Abrasion

– Alkali attack

and ash

reactions

– Size

distribution

– Low reactivity

to CO 2

– Abrasion

resistance

Raceway zone – Generation of CO – Combustion

– Thermal shock

– Graphitisation

– Impact stress

and abrasion

– Strength

against

thermal

shock and

mechanical

stress

– Abrasion

resistance

Hearth zone – Burden support

– Iron and slag

drainage

– Carburisation of iron

– Graphitisation

– Dissolution into

hot metal

– Mechanical

stress

– Size distribution

– Mechanical

strength

– Abrasion

resistance

– Carbon solution

Source : Geerdes et al ., 2009.



In the course of environmental challenges, injection of charcoal as a

renewable carbon containing substance has been studied recently under

BF simulated conditions alone and in the mixture with PC (Babich

et al ., 2010; Machado et al ., 2010). Table 12.6 gives the composition of

used coals and charcoals. The results obtained allow for the following

conclusions:

Combustion behaviour of the tested charcoals is better or comparable •

with mineral coals for injection.

Conversion degree of charcoals under the raceway simulated conditions •

is less dependent on its concentration in the blast than that for mineral

coals (Fig. 12.10).

Tests under BF shaft simulated conditions showed that solution loss reac-•

tion for charcoal goes on faster than for PC. The reaction velocity rises

exponentially with increase of temperature in the range of 900–1300 ° C

(temperatures in the cohesive zone). Difference in reaction rates of char-

coal and mineral coals lowers with rising temperature (Fig. 12.11).

Emission of greenhouse gases in the production and transportation of char-

coal has also to be considered (Hoffman et al ., 2001).

Waste plastics can also be used in the steel industry in different ways to

recycle industrial and municipal wastes and to replace or supplement coal

use. There is industrial experience of plastics injection into the BF via tuy è res

in Germany, Japan and Austria (Buergler et al ., 2007); systematic study on

1200

1000

800

600

Con

sum

ptio

n of

red

ucin

g ag

ents

in k

g/t H

M

400

200

01950 55 60 65 70 1975 80

YearFrom 1991 on including new countries

Ore beneficiationInput of overseas rich ores

Blast temperature >1200 °CO2-enrichment

Top pressureBurden distributionGlas flow control

Improvement of Fe burdenImprovement of coke

Coal

Oil + othersCoke (dry)

Small coke inFe burden

137.8

496.7348.1

10.8

85 90 95 2000 05 2010

12.9 Reducing agent consumption in German blast furnaces (Peters and

Schmoele, 2012 ).

© W

oodhead P

ublis

hin

g L

imite

d, 2

013

Table 12.4 Operating results of best performing European blast furnaces 2008

Country B F FIN D D D NL NL

Works AM

Gent

AM

Dunkerque

Ruukki

Raahe

HKM TKS TKS Tata

Corus

Tata

Corus

BF No.

Hearth diam.

m A

10.0

4

14.0

1

8.0

B

11.0

Ha9

10.2

S 2

14.9

6

11.0

7

13.8

Bell coke

Nut coke

Total coke

kg/t HM

kg/t HM

kg/t HM

261.9

66.5

328.4

266.1

47.8

313.9

319.0

39.0

358.0

289.0

66.8

355.8

262.6

70.9

333.5

289.5

53.5

343.0

245.6

35.3

280.9

271.1

32.1

303.2

Injectants

Coal

Oil

Plastics

Natural Gas

Total injectants

kg/t HM

kg/t HM

kg/t HM

kg/t HM

kg/t HM

169.7

169.7

171.5

171.5

100.5

100.5

23.5

84.9

108.4

147.9

147.9

159.8

159.8

235.1

0.9

236.0

214.9

214.9

Total reductants kg/t HM 498.1 485.4 458.5 464.2 481.4 502.8 516.9 518.1

Productivity

HM production

t/m 3 (WV) × 24 h

Million t

2.18

2.0

2.24

3.1

3.44

1.2

2.57

2.5

2.80

1.7

2.49

4.1

3.18

2.5

2.64

3.6

Source : Peters and Luengen, 2009.



reaction kinetics of waste plastic materials is being performed (Knepper

et al ., 2011).

A BF technology with injection of PC, cold oxygen instead of hot blast

and top gas recycling after removal of carbon dioxide is being developed

and tested (ULCOS, 2011a).

12.4 Coal-based direct reduction processes

DR is defi ned as any process in which metallic iron is produced by reduc-

tion (removal of oxygen) of iron ore or any other iron oxide by avoiding the

liquid melting phase and below the melting temperature of any materials

Table 12.5 Ispat Inland PCI coal selection criteria

Criteria Consideration Desired characteristic

Combustion propensity Carbon form

Char surface area

Lower carbon form

Higher char pore surface

area

Lance plugging

propensity

Ash fusion temp.

Caking index

Higher ash fusion temp.

Lower caking index

Ease of coal conveyance Permeability

Cohesive strength

Higher permeability

Lower cohesive strength

Ease of coal handling Surface moisture

Size of coal feed

to grinders

Low surface moisture

Low percentage of – 28

mesh coal

Coal chemistry Favourable coal ash

chemistry

Low S, P and Cl

Favourable economics Lowest replacement costs

Source : Kruse et al ., 2003.

Table 12.6 Composition of charcoals (oak 2, eucalyptus) and

mineral coals (PC 1, PC 2)

PC 1 PC 2 oak 2 eucal.

Proximate analysis, wt. %

Ash

VM

C fi x

7.49

30.40

ND

10.27

8.60

ND

5.00

24.87

70.16

0.6

18.82

80.69

Ultimate analysis, wt. %

C

O

H

N

S

80.00

6.49

4.5

1.2

0.32

82.80

2.31

3.3

0.9

0.42

84.77

11.42

3.23

0.58

0.00

88.26

8.42

2.71

0.21

0.03

Source : Adapted from Babich et al ., 2010.



involved with use of solid, liquid or gaseous reductants (The International

Standard ISO/CD 11323, 1999). The products of DR processes – DRI, LRI,

HBI and CBI – are described in Section 12.2.1; the term DRI is also often

used for description of all mentioned products.

There are gas based (mainly Midrex and HYl III but also further processes

such as HYLSA IV, Finmet, Circored, Fior, Finmet, Purofer, Armco or Iron

Carbide) and coal-based (e.g. SL/RN, Jindal, Inmetco, Fastmet and Ciomet,

Sidcomet, IDI, Redsmelt, Dryiron, ITmk3) DR processes. Figure 12.12 shows

world DRI production by process in 2010 (World Steel Dynamics, 2011).

Here two examples of coal-based DR processes are introduced.

12.4.1 ITmk3 process

ITmk3, which stands for ‘Ironmaking Technology Mark Three’, is the devel-

opment from Kobe Steel and Midrex (Kikuchi et al ., 2010). In the process

iron nuggets are produced by reduction of iron ore fi nes agglomerated with

pulverised non-coking coal (coal consumption about 500 kg/t) (Chatterjee,

2010).

Figure 12.13 shows the process fl ow. This process of granular ironmaking

comprises (Kikuchi et al ., 2010):

agglomerating iron-ore and coal into composite pellets; •

reducing and melting the pellets; •

separating metallic iron from slag; •

treating exhaust and recovering heat. •

PC 1

eucal.

oak 2

PC 2

70

60

50

40

30

20

10

Con

vers

ion

degr

ee (

%)

Sub

-sto

ichi

omet

ric a

rea

00 1 2 3

O/C atomic ratio

4 5 6

12.10 Conversion rate of charcoals (oak and eucalyptus) and reference

PC (high volatile PC 1 and low volatile PC 2) (Babich et al ., 2010).



The mixture of iron fi nes and pulverised coal with addition of binder is

agglomerated into composite pellets. The pellets, after drying and screening

to a yield of 17–19 mm green balls, are charged into a rotary hearth fur-

nace (RHF) heated to 1350–1450 ° C (Chatterjee, 2010). Final drying of the

pellets as well as coal devolatilisation and iron oxide reduction take place.

The immediate contact between iron oxide and carbon at high temperatures

(1400–1500 ° C) as well as radiation heating in the RHF enable the short

reaction time of 6–10 min. Then, the molten iron is separated from the slag

generated from the gangue and the ash. The fi nal product is iron nuggets,

typically 5–25 mm in size with a high density (7.4–7.6 g/cm 3 ) and composi-

tion, shown in Table 12.7 (Chatterjee, 2010).

100

TG

(%

)

900°C

PC 2

PC 1

eucal.

90

80

70

60

50

40

0 20 40 60 80

Time (min)

100 120 140

(a)

100(b)

80

60

40

20

00 20 40 60 80

Time (min)100

1100°C

PC 2

PC 1

eucal.

TG

(%)

120 140 160

12.11 Reaction rates of charcoal and PC with CO 2 at (a) 900 ° C and

(b) 1100 ° C (Babich et al ., 2010).



Iron oxideconcentrate

Reductant(coal)

Air

Heatrecoverysystem

Flue gas

Dust collector Burner

fuel

Rotary hearthfurnace

Mixer Pelletiser Dryer

Separation

Iron nugget Slag

12.13 ITmk3 process fl ow (Kikuchi et al ., 2010).

Table 12.7 Typical composition

of iron nuggets

Element Percentage

C

P

S

Fe met

2.5–3.0

0.01–0.02

0.05–0.07

96.0–97.0

Source: Chatterjee, 2010, p.353.

Coal-based25.7%

Other gas0.5%

HYL/Energiron14.1%

MIDREX59.7%

12.12 Worldwide DRI production by process in 2010 (World Steel

Dynamics, 2011).



The fi rst commercial ITmk3 plant with annual design capacity of 0.5 Mt,

constructed by Kobe Steel and Steel Dynamics, Inc. (SDI) at Hoyt Lakes,

Minnesota in the USA, began production in 2010 (Harada and Tanaka, 2011).

12.4.2 Circofer ® process

The Circofer ® process is a coal-based direct reduction process developed

by Outotec GmbH. Fine ore is pre-reduced to DRI in a CFB (circulating

fl uidised bed) reactor (Fig. 12.14). Char and hot reducing gas are produced

as by-products.

In the CFB reactor, preheated iron ore is pre-reduced to a degree of met-

allisation of up to 85% with CO and H 2 out of in situ coal gasifi cation. The

reactor off gas is used in one or two preheating stages (depending on desired

off gas temperature) to preheat the cold iron ore making use of the sensitive

heat in the gas. After that, it is cooled and cleaned and the reaction products

water and carbon dioxide are removed (Born et al ., 2011).

Coal is fed directly into the integrated heat generator where it is partially

combusted with pure oxygen. Unburnt coal and char are transferred into

the CFB where the pre-reduction takes place at around 950 ° C, using the

Boudouard reaction to produce CO from coal. The DRI product is continu-

ously discharged from the reactor and fed into a subsequent smelting reduc-

tion process. This can either be a shaft furnace, a submerged arc furnace or

Coal Iron Ore Char Additive

Pneumaticfeed handling

Stage ISteam to

CO2 absorberB.F.W

Steam boiler Bag filter Venturi scrubber

Dust Settling pondCO2

CO2absorber

SteamHot air

Recyclechar

Charsepa-rator

Offgas

Coal Process gascompressor

Char andDRI with85% pre-reduction

CFBstage I

Heatgene-rator

Solids Gas

Processgas heater

Bleed gas

Hismeltsmeltreductionvessel

Hot metalwith 4% C

Slag

Stage IIPreheating

O2

12.14 Scheme of the Circofer ® process combined with Hismelt smelting

vessel. (Source: Adapted from Orth et al ., 2004.)



a smelting reduction process like HIsmelt (Orth et al ., 2004), Fig. 12.14, or

AusIron (Laumann et al ., 2010). The carbon content of the material is 6–8%.

For the production of highly metallised DRI, the CFB is followed by a

bubbling fl uidised bed reactor (FB) where the pre-reduced material is fur-

ther reduced by recycled gas containing mainly CO and H 2 , to a degree of

metallisation of over 90%. After the discharge of the DRI from the FB,

the remaining carbon is removed in a hot magnetic separator. The hot DRI

can be used directly in electric smelting furnaces. The off gas from the FB

is fed into the CFB making full use of the remaining reduction potential.

The re-circulated off gas is used for fl uidisation of the solids in the reac-

tors. Primarily, reduction occurs with carbon monoxide: Fe 2 O 3 + 3CO =

2Fe + 3CO 2 . After heat recovery in a boiler, the de-dusted, quenched and

CO 2 − stripped gas is returned to the fl uidised bed reactors.

The appearance of sticking (DRI particles get bonded to each other) in

the CFD reactor is avoided despite high temperature operation due to (von

Bitter et al ., 1999):

the formation of a protective coating of soot on the metallised iron par-•

ticles generated from the partial cracking of the volatile matters in the

coal;

the presence of volumetrically larger amount of excess carbon (10 times) •

than metallised iron particles;

the short contact time between particles after impinging against each •

other caused by high gas velocity and consequently high kinetic energy

of solid particles.

In the Circofer ® process any coal having an ash melting temperature of

>1050 ° C and volatile matter content of 10–40% can be used. A coal with

ash content <15% is preferable in order to keep the circulating load in

the reactor, and in the case of direct charging into a smelter the slag vol-

ume to a minimum (von Bitter et al ., 1999).

The Circofer ® pilot plant operates at Outotec’s research centre in

Frankfurt, Germany (Laumann et al ., 2010).

12.5 Self-reducing burden materials for the blast furnace and direct reduction

Some agglomerates (pellets and briquettes) have the tendency to swell

enormously in a reducing atmosphere. Swelling or volume increase can

lead to sticking and plating or to the loss of agglomerate strength and their

collapse, which gives rise to operational problems and loss of productivity

of the shaft furnaces such as in OxiCup and Technored processes, but also

in the BF and hinders heat transfer in rotary hearth furnace processes. Iron



ore pellets with cold-embedded carbonaceous materials can be successfully

used in DR processes as well as in BF ironmaking to avoid or hinder swell-

ing of these burden materials and to improve their reduction behaviour.

The reason for producing the briquettes from a mixture of manganese and

iron ores with embedded coal is as follows. Usually manganese is added to

steel as an alloying element in the form of ferromanganese (FeMn); some

new steel grades contain 15–30 wt. % Mn. The manganese utilisation effi -

ciency is relatively low due to its signifi cant losses during benefi ciation, FeMn

production and steelmaking processes. Mn-yield can be increased, e.g. by

direct reduction of the ore in cold bonded agglomerated briquettes (Ohler-

Martins et al ., 2007) in such a way that carbonaceous material and other nec-

essary ingredients can be agglomerated with or without a binder. The oxides

of manganese and iron ores in the agglomerates are reduced to metals, and

the carbon acts as heating source and reducing agent (Ohler-Martins, 2008).

Another target for the application of agglomerates and composites

with embedded high reactive carbonaceous materials is the possibility for

decrease of carbon consumption in the BF by means of transition of FeO-Fe

reduction equilibrium to lower temperature affecting decrease of thermal

reserve zone temperature. This shift would improve the CO-gas utilisation

effi ciency, resulting in lower reducing agent consumption (Naito et al ., 2001;

Ariyama et al ., 2005). Babich et al . (2009) have pointed out that carbon sav-

ing at lower reserve zone temperature while using highly reactive materials

can be realised only under certain conditions.

12.5.1 Self-reducing pellets

The behaviour of self-reducing pellets (SLP) during reduction has been

investigated using the lab rig based on a Tammann furnace combined with

electronic microscopy and the BET method (Wang, 2004). It has been found

that the use of pellets with embedded carbon can hinder or reduce swelling

at 800–1000 ° C and lead to shrinking at higher temperatures (Fig. 12.15).

The volume change depends on the embedded coal rate, reduction temper-

ature and reduction time.

The reduction behaviour of SRP depends also on the type of embedded

carbonaceous material. Better reducibility of SRP with coal and with car-

bon extracts from fl y ash called unburnt carbon (UBC) compared to SRP

with waste plastics (WP) has been proven due to more intensive solid phase

reactions of pellets with dense structure (Fig. 12.16).

12.5.2 Self-reducing briquettes

Self-reducing carbon containing briquettes consisting of Fe-Mn ores have

been suggested and investigated, e.g. as alternative to ferromanganese



(Fig. 12.17) (Ohler-Martins et al ., 2007; Ohler-Martins, 2008). Briquettes

produced from a mixture of manganese ore (28 to 78 mass%), iron ore (52

to 0 mass%) and coal (about 20 mass%) were reduced in the electric heated

furnace in the temperature range of 1000–1400 ° C.

Figure 12.18 illustrates the degree of metallisation (MD) for Fe and

Mn as a function of the temperature and time of reduction. The MD for

Fe reached already at 1100 ° C and 30 min of reduction time was 83.3%.

The maximum MD for Mn was 70% at 1300 ° C and 50 min of reduction

time.

Apart from the manufacture of low priced ferromanganese, the proposed

carbothermic reduction of briquettes consisting of Mn and Fe ores has further

20

0

–20

–40

–60

–80700 800 900 1000

Temperature (°C)

Reduction time: 30 min

Sw

ellin

g de

gree

(%

)

1100 1200 1300

18% LVC

14% LVC

10% LVC

6% LVC

12.15 Volume change of hematite pellets with embedded low volatile

coal (LVC) (Babich et al ., 2003; Wang, 2004).

12.16 Polished sections of self-reducing pellets with UBC (left) and WP

(right) (Babich et al ., 2003; Wang, 2004).



(c)

Slag

(d)

Metal

10 mmIEHK

(b)(a)

12.17 Photos of briquette before reduction (a), during reduction (b),

in the crucible before reduction (c) and after reduction at T > 1200°C,

molten phase of slag and metallic regulus (d) (Ohler-Martins, 2008).

potential applications, e.g. for the recycling of in-plant waste oxide materials, for

partial replacement of coke with coal as a reducing agent or for production of a

material with suitable carbon content prior to smelting in an electric furnace.

12.5.3 Iron ore–carbon composites

Pressed iron ore–coal mixtures or composites are being studied (particularly

intensively in Japan), aiming at shifting the reduction processes in the BF

to lower temperatures and so reducing the carbon consumption (Nomura

et al ., 2007; Ariyama et al ., 2010).

The composite consisting of both iron oxide to be reduced and a reducing

agent can be considered a microreactor. Such an iron ore–carbon composite is

assumed to be a highly reactive burden able to decrease the reaction temperature,



because it is composed of fi ne materials, which are in close contact with each

other (Ueda et al ., 2009). The favourable reduction behaviour of the iron ore–

carbon composites have been reported in several experimental and theoretical

studies (e.g. Naito, 2006; Ueda et al ., 2009). Many carbonaceous materials, such

as coal, coke, biomass or plastic wastes have been examined as possible reduc-

tants for the composites (Murakami and Kasai, 2011). Carburisation behaviour

of composites is being studied as well (Ohno et al ., 2012).

12.6 Smelting reduction processes

‘Smelting Reduction’ (SR) means a group of processes which produce liquid

hot metal from iron ore without their agglomeration and without using coke

(in reality, a small amount of coke is usually needed). SR processes can be

classifi ed into two groups.

1. Melter-gasifi er where the process takes place in two stages:

(i) reduction of iron ore to produce DRI (~850–1050 ° C);

(ii) melting under a reducing gas.

2. Iron bath reactor.

Examples of both reactor types are given below.

12.6.1 Coal, coke, briquettes and PCI use in the Corex ® and Finex ® processes

Mainly two SR processes are commercially proven: Corex ® and Finex ® ; sev-

eral plants operate in South Korea, South Africa, India and China. The met-

allurgical work is carried out in two separate reactors, the reduction shaft

100M

G fo

r F

E (

%)

90

80

70

60

50

40

30

20

10

010 30 50

Time (min)

Fe

1273K 1373K 1473K 1573K

100

MG

for

MN

(%

)

90

80

70

60

50

40

30

20

10

010 30 50

Time (min)

Mn

1273K 1373K 1473K 1573K

12.18 Briquette metallisation degree for Fe (left) and Mn (right) of non-

isothermal trials as function of temperature and time (100 vol − % Ar,

fl ow rate 2.5 L/min) (Ohler-Martins, 2008).



(Corex ® ) or fl uidised-bed (Finex ® ) and the melter-gasifi er ( Fig. 12.19). Coal

or coal briquettes enter the dome of the melter-gasifi er and is converted to

char at 1100–1150 ° C. Oxygen is blown into the melter-gasifi er and generates

a reduction gas upon gasifi cation of the coal. This gas (mainly CO + H 2 ) is fed

to the upper reactor(s), where the burden is reduced. The reduced iron ore or

hot DRI is charged into the melter-gasifi er, where it is smelted into hot metal

and molten slag. The tapping procedure, tapping temperature and further

processing of the hot metal are the same as with blast furnace hot metal.

The Corex ® process requires a high amount of non-coking coal

(750–950 kg/tHM) with well-defi ned properties and some amount of coke

(10–20%, usually 50–150 kg/tHM) for heat generation, production of reduc-

ing gases and to maintain char bed permeability (Prachethan Kumar et al ., 2009). Coal should satisfy certain physical, chemical, physico-chemical,

physical and mechanical properties.

The coal property parameters for Corex ® and Finex ® processes are very

similar to those for BF coke (Tables 12.8, 12.9, and 12.10). The requirements

for Corex ® coals are lower compared to the requirements for coals for coke-

making (Wieder et al ., 2004a).

Coke quality required for the Corex ® plant in comparison with the coke

qualities typically used in the blast furnace is shown in Table 12.11.

Injection of low grade PC can decrease the consumption of high quality

coal. Using PCI technology to inject the de-dusted coal fi nes into the melter-

gasifi er can increase the resource recycling and decrease hot metal costs

(Zhang et al ., 2009). PC injection and its inter-reaction with char generated

Lump ore/pelletslump ore/pellets

additivesLump ore/pellets

additivesFine ore

additive fines

Coal(briquettes)

Exportgas

Exportgas

Hot metalslag

Hot metalslag

Oxygen(PCI)

Oxygen(PCI)

Coalbriqueltes

(a)(b)

12.19 Corex ® and Finex ® process fl ow sheets (Wieder et al ., 2009)

(a) Corex process; (b) Finex process (simplifi ed, without gas cleaning

circuit).



in the melter-gasifi er are being studied (Knepper, 2012). It should be

stressed that Corex ® raceway geometry (extension and shape) and param-

eters (temperature, gas composition and volume) differ from those in the

BF; e.g. adiabatic fl ame temperature can be around 3500 ° C (Barman et al ., 2011) whereas this value in the BF raceway is typically in the range of 2100–

2300 ° C (Babich et al ., 2008).

12.6.2 Coal use in the HIsmelt process

The principle of the HIsmelt process developed by Rio Tinto is the reduction

and smelting of iron ores with dissolved carbon in a metal bath. This is achieved

Table 12.8 Typical specifi cations of coal for Corex ®

Parameter Preferred value

Moisture in coal

Fixed carbon

Volatile matter

Ash

Sulphur

Char strength after reaction (CCSR)

Char reactivity index (CCRI)

Heat of cracking

Mean particle size (MPS)

<4%

>59%

25–27%

<11%

<0.6%

>45% (+10 mm)

<35%

Lower the better (kJ kg − 1 )

19–22 mm

Source: Prachethan Kumar et al ., 2009.

Table 12.9 Specifi cation for Corex ® coals

Coals for

blending

Coal or coal blends

Tolerable Preferred

Moisture

before dryer

after dryer

max 15% max 12%

max 5%

<8%

<5%

Proximate analysis (dry)

Fixed carbon

Volatiles

Ash

Fixed carbon/Ash

min 50%

max 40%

max 30%

min 55%

max 35%

max 25%

min 3%

55–65%

25–35%

5–12%

<5%

Sulphur (dry) – – <0.5%

Grain size 0–50 mm 0–50 mm

>50% + 15 mm

<10% − 2 mm

<5% − 1 mm

8–40 mm

d 50 : 20–30 mm

<5 %–8 mm

Source: Wieder et al ., 2004b.



by the injection and partial combustion of coal directly into the bath and by

transferring the heat generated by post-combustion of the evolved gases from

the bath with oxygen enriched hot blast back to the bath. The overall reactions

and heat transfer mechanism provide suffi cient energy to maintain the reduc-

tion reactions and provide the heat for smelting of the iron and slag.

The oxidising atmosphere and the low temperature slag in the HIsmelt

reactor results in partitioning of 90–95% of the input phosphorus to the slag.

This opens the potential for the use of high phosphorus ores for high-quality

pig iron production (Buckley and Gull, 1999).

The off gas exits the top of the reactor at temperatures signifi cantly hotter

than that of the BF but with similar calorifi c value.

Coal injected into the HIsmelt process passes through and/or reacts in four

different regions within the smelt reduction vessel (Fig. 12.20) (Campbell

et al ., 1999):

Table 12.10 Additional criteria for Corex ® coal

Criteria: Guideline value: Remark:

Chlorine

Swelling Index

max 0.04%

upto 6

Corrosion

Thermo-mechanical Stability

+10 mm

− 2 mm

+10 mm

− 2 mm

Reactivity of Char

RI

RSI>5

min 70%

max 5%

min 25%

max 22%

max 50%

min 40%

After pyrolysis

After NSC drum 600 rev.

CO 2 , 1100 ° C, 60 min

+5 mm after NSC drum

Mechanical Strength of Coal

+10 mm

− 2 mm

min 70%

max 16%

After Micum drum 100 rev.

Source : Wieder et al ., 2004b.

Table 12.11 Coke quality for BF and Corex ®

Minimum requirement for high

productivity blast furnaces, current

and future

Minimum

requirement for

COREX ® , current

and future

Grain Size

Ash

Sulphur

CSR

CRI

+25 mm (93%)

<10%

<0.7%

>60%

<25%

+25 mm (96%)

<8.5%

<0.65%

>61% (65%)

<22%

10–15 mm

<15%

<1%

>55%

<35%

Source: Wieder et al ., 2004b.



the plume at the end of the injection lances; •

pyrolysis and volatiles yield region; •

dissolution and capture of carbon by the bath; •

top space where combustion occurs to supply energy for the system. •

The commercial HIsmelt plant with a capacity of 0.8 Mt/a was built by Rio

Tinto, together with Nucor Steel, Mitsubishi and Shougang Steel at Kwinana,

Western Australia (Goodman and Dry, 2009). It is planned to relocate this

plant to India at Jindal Steel and Power Ltd (JSPL) (Anon., 2011a).

The HIsarna process has recently been developed which represents the

merging of HIsmelt and Cyclone Converter Furnace (CCF) technologies. It

also produces liquid hot metal on the basis of fi ne ores and coal (Fig. 12.21).

The two step process uses a cyclone, where the fi ne ore is pre-reduced and

melted, and an iron bath reactor where the ore is fi nally reduced. Contrary

to the conventional HIsmelt process, the pyrolysis of the coal takes place

outside the process in a reactor, which uses the heat generated by degassing

the coal (Luengen et al ., 2011b).

Coal is injected at high velocity (using a carrier gas such as nitrogen) into

the bath. The primary process objective for coal is to dissolve carbon into

Coal, ore, fluxesin N2 suspension

Processdust

Combustionin top space

Char capturein slag

Slag

Injectionplume

Metal

Coal pyrolysis andvolatile yield

Carbondissolution& capture

Char particle withsoot & volatiles

Char dissolution

Char by-pass

Soot by-pass

12.20 Coal travelling through the HIsmelt process (Campbell et al ., 1999).



the metal to replace dissolved carbon which is used in the smelting step.

Coal injection conditions are critical, and the metal bath temperature makes

up 1400–1450 ° C with dissolved carbon around 4.0% (Meijer et al ., 2011).

A pilot HIsarna plant with a nominal capacity of 60 000 t/a was built

in 2010 in IJmuiden, the Netherlands (Luengen et al ., 2011b ; Meijer et al ., 2011).

12.7 Electric steelmaking and further uses of carbon in iron and steel metallurgy

Beside of electric arc furnace, carbon use in refractory materials and in

mould powder for continuous casting is presented in this section

12.7.1 Electric steelmaking

In EAF scrap or DRI/HBI is smelted in a vessel with an electric arc.

Graphite electrodes

Graphite electrodes serve to transfer the electrical energy from the power

supply to the steel melt in the EAF bath. They are typically made using pre-

mium petroleum needle coke, coal tar pitch, and some additives (Fruehan,

1998). Specifi cation of needle coke for the manufacture of large diameter

graphite electrodes is shown in Table 12.12.

Electrode consumption varies between 1.8 and 9.9 kg/t of liquid steel

(Parkash, 2010) depending on the process characteristics and electrode

Oxygen plant

Oxygen

Dust

Energy recovery

95%CO2(dry)

Hotmetalslag

Hotchar

Volatiles

Ore fines

Coal

Ful

lyco

mbu

sted

12.21 Hisarna concept (Luengen et al ., 2011).



quality. Ameling et al . (2011) reported that the electrode consumption in

Germany in 2010 was approximately 1.1 kg per ton as a result of the reduc-

tion of time between the taps to 40 min and consequently the lower electric-

ity consumption (345 kWh/t). Electrodes are classifi ed as regular grade or

premium grade on the basis of their physical properties (International Iron

and Steel Institute, 1983).

Charge carbon

Charge carbon is used in the EAF to consume excess oxygen during melt-

ing and to minimise the oxidation of alloys. Different carbon containing

materials are used for these purposes, e.g. anthracite, coal, metallurgical

coke, calcined pet coke, synthetic graphite or silicon carbide. The charge

carbon can be substituted by carbon contained in steel scrap, DRI/HBI

and in pig iron.

Coal injection

Slag foaming in the EAF increases the effi ciency of energy transfer from

graphite electrodes to the steel bath. The formation of desired slag foam-

ing can be provided by injection of coal or further C-containing materials

like anthracite, metallurgical coke, calcined pet coke, fl uid coke breeze or

synthetic graphite. The effect of coal characteristics like its grade and size

on this process has been investigated; further carbonaceous materials like

acetylene and petrol cokes have been tested as well (Fig. 12.22) (Zulhan,

2006). The experiments were conducted in a 5 kg EAF (Fig. 12.23).

Analyses of used carbonaceous materials are given in Table 12.13. The

height of slag foaming during the injection of carbonaceous material

has been determined using a digital video camera. An optimal grain size

of the examined carbonaceous materials is in the range of 0.5–0.7 mm.

Table 12.12 Typical needle coke specifi cation for graphite

electrodes

Specifi cation Units Amounts

Ash

Apparent density

Porosity

Transverse strength

Young Modulus

Electrical resistance

Coeffi cient of thermal

expansion (CTE)

wt. − %

g/cm 3

%

N/mm 2

× 10 3 N/mm 2

× 10 6 Ω .mm

× 10 − 6 / ° C

0.2

1.6–1.72

22–28

9–13.8

6.21–9.66

45.7–83.8

2.16–3.24

Source: Parkash, 2010.



Furthermore, the chemical composition of the carbonaceous materials

infl uences the formation of slag foaming. The ash in carbonaceous mate-

rials, which contains approx. 40–60% SiO 2 , improves the foaming stability.

On the other hand, the ash content reduces the gas velocity which sup-

ports the slag foaming.

About 30–35% of total energy consumption in the EAF is realised by

carbon.

12.7.2 Further uses of carbon in iron and steel metallurgy

Carbon in various forms is used for many further metallurgical applications.

Two examples are given below.

12.22 SEM images of the examined carbonaceous materials (Zulhan,

2006).



Refractories

The iron and steel industry is the main consumer of refractories; its share

makes up 65–70% of all industries (Buhr, 1999). They are used for lining fur-

naces (e.g. BF, BOF, EAF), for hot metal transport, in vessels for secondary

metallurgy, in continuous casting, and for heating metal in furnaces before

further processing, e.g. during start-up in continuous casting.

Carbon refractory is a group of refractories consisting almost entirely of

carbon or containing from 4 to 35% carbon in addition to other refractory

components (oxide-carbon refractories). Refractories use various graphite

forms in combination with oxides to impart special properties. These refrac-

tories maintain the high corrosion resistance to slag, while enhancing ther-

mal shock resistance. Table 12.14 shows the properties of several types of

graphite.

Mould powder for continuous casting (CC)

More than 90% of worldwide produced steel is solidifi ed into a ‘semi-

fi nished’ billet, bloom, or slab for subsequent rolling in the fi nishing mills

12.23 Laboratory DC-EAF (left) and slag foaming (right) (Zulhan, 2006).

Table 12.13 Proximate analysis of carbonaceous materials

Coal A Coal B Coal C Coal D Petrol coke Acetylene

coke

VM

Ash

Moisture

C fi x

27.0

7.34

9.5

65.66

9.2

6.14

6.4

84.66

2.4

10.0

12.0

87.6

2.75

7.25

7.5

90.0

0.5

1.0

0.5

98.5

0.45

0.05

0.2

99.5

Source: Adapted from Zulhan, 2006.



using the continuous casting process. Mould fl ux performs fi ve basic func-

tions (Anon., 2011b):

1. Thermally insulates the molten steel meniscus to prevent premature

solidifi cation.

2. Protects the molten steel in the mould from reacting with atmospheric

gases.

3. Absorbs products of de/reoxidation from the molten steel.

4. Provides a lubricating fi lm of molten slag to prevent the steel from

adhering to the mould wall and to facilitate strand withdrawal.

5. Modifi es thermal heat removal in the mould.

Mould powder contains usually about 4–10% of carbon to control the

smelting behaviour of the powder. The typical source of carbon is fl y ash but

also other carbon sources are used, e.g. natural graphite. Moulds in horizon-

tal CC partly consist of pure graphite to remove the heat of solidifi cation

and to control friction between strand and mould.

12.8 Future trends: a steel industry without coal?

About 70% of worldwide crude steel production is based on coal metal-

lurgy using the primary metal from the BF or from the coal-based DR and

SR processes. Electric steel, made by scrap melting in the EAF, also needs

some carbon, e.g. for electrodes and injection. Secondary metallurgy, con-

tinuous casting and lining for metallurgical aggregates (refractories) are

further carbon consumers.

In the past, trends in energy intensive branches considered the proved

reserves, the production and the foreseen consumption of major energy

Table 12.14 Typical properties of graphite

Properties Amor -

phous

Flake High

crystalline

Primary

artifi cial

Secondary

artifi cial

Carbon (wt. − %)

Sulphur (wt. − %)

True density (kg/m 3 )

Graphite content

(wt. − %)

Ash true density (kg/m 3 )

Resistivity ( Ω .m)

Morphology

81.0

0.1

2310

28

2680

0.00091

Granular

90.0

0.1

2290

99.9

2910

0.00031

Flaky

96.7

0.7

2260

100

2890

0.00029

Plate,

Needles,

Granular

99.9

0.001

2250

99.9

2652

0.00035

Granular

99.0

0.01

2240

92.3

2680

0.00042

Granular

Source: Fruehan, ed., 1998.



sources: natural gas, oil and coal. Meanwhile the driving force of devel-

opment has shifted to environmental issues. Mitigation of CO 2 emissions

caused by use of fossil energy sources like oil and coal is the biggest chal-

lenge facing the steel industry. It can be achieved:

1. by CO 2 removal from the process

using CCS technology. The high CO • 2 concentration in the metallur-

gical gases (e.g. 20–25% in the BF top gas) facilitates the capture

process.

using CO • 2 in chemical, biological and further processes, e.g. for pro-

duction of bio-based chemical raw materials and products, pharma-

ceuticals, etc.

2. by renewable carbon sources (biomass)

3. by use of hydrogen instead of carbon. The crucial point thereby is mass

hydrogen production at a reasonable price; a remarkable increase in

crude steel production is forecast for the next decades. Besides hydro-

gen generation using electrolysis, water steam reforming, partial oxida-

tion of hydrocarbons, fermentation or photosynthesis, other available

sources like natural gas or coke oven gas should also be considered.

It is conceivable that the traditional coal-based steel industry (BF-BOF

route) could switch to alternative energy sources like renewable, nuclear

energy, electrical heat using plasma or microwave technologies, or could

even in the more distant future be replaced with other ironmaking methods

like microbiological technologies.

It is expected that the following short and middle term solutions will be

developed and introduced to mitigate CO 2 from steelmaking:

signifi cant increase in carbon effi ciency; •

partial use of biomass and waste plastics in existing metallurgical •

technologies;

capture carbon dioxide from existing processes, such as BF and proba-•

bly Corex ® (with recycling of CO 2 -lean top gas (ULCOS, 2011a; Wu et al ., 2011) and obviously from new ones, such as ULCORED or Hisarna

(ULCOS, 2011b);

Combination of different routes and technologies, e.g. use of coke oven •

gas for DRI production (Diemer et al ., 2011), use of Corex ® top gas

mixed with a portion of melter-gasifi er off gas for Midrex (Tsvik, 2011),

and possibly a Hydrogen Rich Blast Furnace, where minimum coke

amount will be required only as the burden supporter and carburiser.

It should fi nally be mentioned that the discussed trends, challenges and fi g-

ures are related to the steel industry in industrial countries characterised



by the best available technologies. Diversity of technological levels, policies

and priorities in different regions of the world is enormous.

It can be summarised that a question posed in the title of this section,

‘… a steel industry without coal?’, can be answered as follows: lower carbon

consumption is possible but not without it .

12.9 Sources of further information and advice

Books and book chapters

Babich, A., Senk, D., Gudenau, H. W. and Mavrommatis, K. (2008), ‘ Ironmaking, Textbook ’, Aachen, Mainz GmbH, 402 p.

Chatterjee, A. (2010), ‘ Sponge Iron Production by Direct Reduction of Iron Oxide ’,

PHI Learning Private Ltd., New Delhi, 353.

D í ez, M. A., Alvarez, R. and Barriocanal, C. (2002), ‘Coal for metallurgical coke pro-

duction: prediction of coke quality and future requirements for cokemaking’,

International Journal of Coal Geology , 50 , 389–412.

Habashi, F., ed. (1997), ‘ Handbook of Extractive Metallurgy ’, Weinheim, Chichester,

New York, Toronto, Brisbane, Singapore, WILLEY-VCH, 1 and 2.

Ishii, K., ed. (2000), ‘ Advanced pulverised coal injection and blast furnace operation ’,

Pergamon, Elsevier Science Ltd., Oxford, UK, 307.

Pajares, J. A. and D í ez, M. A. (2005), ‘ Encyclopaedia of Analytical Science’ , 2 nd

Edition: Coal and Coke, Elsevier, Oxford, 182–197.

Seetharaman, ed. (2005), ‘ Fundamentals of Metallurgy ’, Cambridge, England,

Woodhead Publishing Ltd, 574.

Von Bogdandy, L. and Engell, H.-J. (1971), ‘ The Reduction of Iron Ores ’, Berlin,

Heidelberg, New York, Springer Verlag; Duesseldorf. Stahleisen m.b.H.

Resources on web sites

AME group (2011), ‘Metallurgical Coal’, available from: http://www.ame.com.au/

metcoal.htm

CoalTech Pty Ltd (2011), ‘Coal technology’, available from: http://www.coaltech.

com.au

JFE 21 st Century Foundation (2011), ‘An Introduction to Iron and Steel Processing’,

available from: http://www.jfe-21st-cf.or.jp/index2.html

World Steel Dynamics, available from: http://www.worldsteeldynamics.com

World Steel Association, available from: http://www.worldsteel.org

12.10 References Ameling, D., Endemann, G., Igelb ü scher, A. and Kesseler, K. (2011), ‘Carbon

Dioxide: Curse or Future?’, Proc. METEC InSteelCon ® 2011, 1st International Conference on Energy Efficiency and CO2 Reduction in the Steel Industry (EECRSteel) (27 June–1 July 2011), D ü sseldorf, Germany

(on CD-ROM).



American Society for Testing and Materials (1993), ASTM D 5341 93, ‘Standard Test

Method for Measuring Coke Reactivity Index (CRI) and Coke Strength After

Reaction (CSR)’.

Anon. (2011a), ‘Rio Tinto makes Hismelt progress in steel making’, Available from:

http://www.im-mining.com/2011/08/18/rio-tinto-makes-hismelt-progress-in-

steel-making, posted on 18 August 2011 [Accessed 16 September 2011].

Anon. (2011b), ‘The fi ve basic functions of mold fl ux’, The Technical Service

Department of Stollberg Inc., Available from: www.rtvanderbilt.com/vand _

mf.ppt, [Accessed 15 September 2011].

Arendt, P., Luengen, H. B. and Reinke, M. (2006), ‘Conventional slot oven or heat

recovery oven?’, Stahl und Eisen , 126 (1), 17–26.

Ariyama, T., Ishii, J. and Sato, M. (2005), ‘Reduction of CO 2 Emissions from inte-

grated steel works and its subjects for a future study’, ISIJ International , 45 ,

1371–1378.

Ariyama, T., Ueda, S., Natsui, S., Inoue, R. and Sato, M. (2010), ‘Recent progress and

future perspective on ironmaking for CO 2 mitigation’, Proc. German – Japanese Workshop ‘Challenges in Ironmaking’, 2 July 2010, Aachen (on CD-ROM,

ISBN: 978-3-934840-10-2).

Babich, A., Gudenau, H. W. and Senk, D. (2003), ‘Optimisation of energy consump-

tion in ironmaking processes by combined use of coal, dust and waste’, Proc. 3rd Int. Conference on Science and Technology of Ironmaking (ICSTI) , 16–20 June

2003, D ü sseldorf, 89–94.

Babich, A., Senk, D. and Gudenau, H. W. (2006), ‘Coke quality for a modern blast

furnace’, Proc.4th Int. Congress on the Science and Technology of Ironmaking (ICSTI’06) , 26–30 November 2006, Osaka, Japan, 351–354.

Babich, A., Senk, D., Gudenau, H. W. and Mavrommatis, K. (2008), Ironmaking Textbook , Aachen, Mainz GmbH.

Babich, A., Senk, D. and Gudenau, H. W. (2009), ‘Effect of coke reactivity and

nut coke on the blast furnace operation’, Ironmaking and Steelmaking , 36 (3),

222–229.

Babich, A. (2009), ‘Online course ironmaking, lecture blast furnace’, Available from:

http://metallurgie.iehk.rwth-aachen.de [Accessed 5 September 2011].

Babich, A., Senk, D. and Fernandez, M. (2010), ‘Charcoal behaviour by its injection

into the modern blast furnace’, ISIJ International , 50 (1), 81–88.

Barman. S. C., Mrunmaya, K. P. and Ranjan, M. (2011), ‘Mathematical model devel-

opment of raceway parameters and their effects on Corex process’, Journal of Iron and Steel Research International , 18 (5), 20–24.

Bender, W., Klima, R., Luengen, H. B. and Wuppermann, C.-D. (2008), ‘Resource

effi ciency in the steel industry in Germany – status 2008’, Stahl und Eisen ,

128 (11), S125–S140.

Bonte, L., Sergeant, R., Daelman, A., Dauwels, G. and Huysse, K. (2005), ‘Infl uence

of the coke and burden quality on the productivity of the blast furnace’, Stahl und Eisen , 125 (6), S5–S10.

Born, S., Stefan, T., Babich, A., Senk, D. and Gudenau, H. W. (2011), ‘Behaviour of

DRI / LRI in CO-CO2-O2-Gas Atmospheres’, Proc. METEC InSteelCon ® 2011, 6th European Coke and Ironmaking Congress (ECIC) , 27 June–1 July

2011, D ü sseldorf, Germany (on CD-ROM).



Buckley, M. J. and Gull, S. D. (1999), ‘Value of HIsmelt ® pig iron to steelmakers, Mini

and Integrated Mills in the New Millennium’, Atlanta, Georgia.

Buergler, T., Brunnbauer, G., Pillmair, G. and Ferstl, A. (2007), ‘Waste plastics as

reducing agent in the blast furnace process – Synergies between industrial

production and waste management processes’, Proc. 3rd Int. Steel Conf. on New Developments in Metallurgical Process Technology (11–15 June 2007),

D ü sseldorf, Germany, 1037–1043.

Buhr, A. (1999), ‘Refractories for Steel Secondary metallurgy’, CN-Refractories , 6 (3),

19–30.

Campbell, A. P., Dry, R. J. and Perazzelli, P. A. (1999), ‘Coal and the versatile Hismelt

process’, Proc. Advanced Clean Coal Technology International Symposium 1999 ,

1–2 November 1999, Tokyo, Japan, 1–6.

Chatterjee, A. (2010), Sponge Iron Production by Direct Reduction of Iron Oxide ,

PHI Learning Private Ltd, New Delhi

CoalTech (2007), Coal technology. Available from: http://www.coaltech.com.au

[Accessed 7 September 2011].

Diemer, P., Luengen, H. B. and Reinke, M. (2011), ‘Utilization of coke oven gas for

the production of DRI’, Proc. METEC InSteelCon ® 2011, 6th European Coke and Ironmaking Congress (ECIC) , D ü sseldorf, Germany, 27 June–1 July 2011

(on CD-ROM).

Eichelkraut, H. (2011), ‘Design and commissioning of the new steel mill complex of

ThyssenKrupp CSA in Brazil’, 42th Steelmaking Seminar- International , 15–18

May 2011, Salvador.

Fruehan, R. J., ed. (1998), ‘ The Making, Shaping and Treating of Steel – Steelmaking and Refi ning Volume ’, AISE Steel Foundation, 525–661.

Geerdes, M., Toxopeus, H. and van der Viert, C. (2009), ‘ Modern Blast Furnace Ironmaking, an Introduction ’, Amsterdam, IOS Press BV.

Goodman, N. and Dry, R. (2009), ‘HIsmelt process’, Available from: http://www.123xu.

com/sj/3311.htm [Accessed 7 September 2011].

Gudenau, H. W., Mulanza, J. P. and Sharma, R. (1990), ‘Carburisation of cast iron by

industrial cokes’, Steel Research , 61 (6), 97–104.

Gudenau, H. W., Meier, L. and Schemann, V. (1998), ‘Coke quality requirements for

modern blast furnace operation’, Cokemaking International , 10 (1), 36–40.

Hanrot, F., Sert, D., Delinchant, J., Pietruck, R., B ü rgler, T., Babich, A., Fern á ndez,

M., Alvarez, R. and Diez, M. A. (2009), ‘CO 2 mitigation for steelmaking using

charcoal and plastics wastes as reducing agents and secondary raw materials’,

Proc. 1st Spanish National Conference on Advances in Materials Recycling and Eco – Energy , 12–13 November 2009, Madrid.

Harada, T. and Tanaka, H. (2011), ‘Commercialisation of ITmk3 ® Process’, Proc. METEC InSteelCon ® 2011, 6th European Coke and Ironmaking Congress (ECIC) , (27 June–1 July 2011), D ü sseldorf, Germany (on CD-ROM).

Hoffmann, A., Wright, R., Kochanski, U., Schumacher, R. and Kim, R. (2001),

‘Design and construction of coke ovens by TKEC on the non-recovery plant of

Illawarra Coke Company in Coalcliff, New South Wales, Australia’, Cokemaking International , 3 (2), 62–66.

International Iron and Steel Institute (1983), ‘ The Electric Arc Furnace ’, Brussels,

Committee on Technology, International Iron and Steel Institute.



International Mining (2011), Rio Tinto makes Hismelt progress in steel making,

Available from: http://www.im-mining.com/2011/08/18/rio-tinto-makes-hismelt-

progress-in-steel-making, Posted on 18 August 2011 [Accessed September 2011].

Jones, H. V. and Kruse, C. W. (1982), ‘Proposed techniques for evaluating chars

made from high-sulfur Illinois coals for manufacture of formed coke’, Illinois

Department of Energy and Natural Resources, State Geological Survey

Division.

Kalinin, A. and Campos, R. (2010), ‘First heat-recovery coke plant in Brazil’, MPT International , 6, 30–32.

Kikuchi, S., Ito, S., Kobayashi, I. and Tokuda, K. (2010), ‘ITmk3 process’, KOBELCO Technology Review , 29 , 77–84.

Knepper, M., Babich, A., Senk, D., Schuster, S. and Feilmayr, C. (2011),

‘Characterisation of waste plastics for the injection into the blast furnace’, Proc. METEC InSteelCon ® 2011, 6th European Coke and Ironmaking Congress (ECIC) , (27 June–1 July 2011), D ü sseldorf, Germany (on CD-ROM).

Knepper, M. (2012), ‘Verminderung des Energieverbrauchs in Schacht ö fen’, Dr.-Ing.

Thesis, RWTH Aachen, forthcoming.

Kruse, R. J., Chaubal, P. C., Moore, J. B. and Valia, H. S. (2003), ‘Blast furnace PCI

coal selection at ispat inland’, Proc. ISSTech Conference , 27–30 April 2003,

Indianapolis, Indiana, 787–797.

Laumann, M.-D., Nepper, J.-P., Sneyd, S. and Stefan, T. (2010), ‘The Vale VII Direct

Reduction Seminar’, Proceedings of the Vale VII Direct Reduction Seminar ,

7–11 November 2010, Muscat/Oman.

Liszio, P. (2003), ‘Neue Kokerei Schwelgern sichert zukunftsorientierte

Kokserzeugung’, Stahl und Eisen , 123 (6/7), 51–54.

Luengen, H. B., Peters, M. and Schm ö le, P. (2011a), ‘Iron making in western Europe’,

Proc. Iron and Steel Technology Conference (AISTech 2011) , 2–5 May 2011,

Indianapolis, Indiana, USA, Vol. I, 387–400.

Luengen, H. B., Endemann, G. and Schmoele, P. (2011b), ‘Measures to reduce

CO 2 and other emissions in the steel industry in Germany and Europe’, Proc. METEC InSteelCon ® 2011, 6th European Coke and Ironmaking Congress (ECIC) , D ü sseldorf, Germany, 27 June–1 July 2011 (on CD-ROM).

Machado, J., Os ó rio, E., Vilela, A., Babich, A., Senk, D. and Gudenau, H. W. (2010),

‘Reactivity and conversion behaviour of Brazilian and imported coals, char-

coal and blends in view of their injection into blast furnaces’, Steel Research International , 81 (1), 9–15.

Matsubara, K., Miyazu, T. and Takahashi, R. (1983), ‘Usage of Gondwana coals for

metallurgical coke making in Japan’, Proc. Symposium on Gondwana Coals ,

Lisbon, Portugal.

Meijer, K., Guenther, C. and Dry, R. J. (2011), ‘HIsarna pilot plant project’, Proc. METEC InSteelCon ® 2011, 1st International Conference on Energy Effi ciency and CO2 Reduction in the Steel Industry (EECRSteel) , D ü sseldorf, Germany, 27

June–1 July 2011 (on CD-ROM).

Men é ndez, J. A., Á lvarez, R. and Pis, J. J. (1999), ‘Determination of metallurgical coke

reactivity at INCAR: NSC and ECE-INCAR reactivity tests’, Ironmaking and Steelmaking , 26 (2), 117–121.

Murakami, T. and Kasai, E. (2011), ‘Reduction mechanism of iron oxide–carbon

composite with polyethylene at lower temperature’, ISIJ International , 51 (1),

9–13.



Naito, M., Okamoto, A., Yamaguchi, K., Yamaguchi, T. and Inoue, Y. (2001),

‘Advanced approach to intelligent ironmaking processes. Improvement of blast

furnace reaction effi ciency by use of high reactivity coke’, Tetsu-to-Hagane ,

87 (5), 357–364.

Naito, M. (2006), ‘Development of Ironmaking Technology’, Nippon Steel Technical

Report No. 94, July 2006.

Nashan, G., Rohde, W. and Wessiepe, K. (2000), ‘Some fi gures and facts on the pre-

sent status and new proposals for a future-oriented cokemaking technology’,

Cokemaking International , 12 (2), 50–55.

Neuwirth, R. and Schuster, D. (2003), ‘State-of-the-art plant technology for coke-

making’, MPT International , 5, 38–48.

Nightingale, R. J., Chew, S. J., Austin, P. R. and Mathieson, J. G. (2002), ‘Assessment

of blast furnace deadman condition’, Proc. Int. Blast Furnace Lower Zone Symposium , 25–27 November 2002, Wollongong, Australia.

Nomura, S., Kitaguchi, H., Yamaguchi, K. and Naito, M. (2007), ‘The characteristics

of catalyst-coated highly reactive coke’, ISIJ International , 47 , 245–253.

Ohler-Martins, K., Gorbunova, E. and Senk, D. (2007), ‘Combined reduction of man-

ganese ore and iron ore and application in the direct and smelting reduction

for producing novel high manganese steels’, Proc. 3rd Int. Steel Conference on New Developments in Metallurgical Process Technology , 11–15 June 2007,

D ü sseldorf, Germany, 8–15.

Ohler-Martins, K. (2008), ‘Metallurgische Mechanismen bei der Direkt- und

Schmelzreduktion von Manganerz und Eisenerz’, Dr.-Ing. Thesis RWTH Aachen.

Ohno, K., Babich, A., Senk, D., Gudenau, H. W. and Shimizu, M. (2012), ‘Effects

of carbon crystallinity and ash in charcoal on carburization reaction’, Proc. 4th International Conference on Process Development in Iron and Steelmaking (SCANMET IV) , 10–13 June 2012, Lule å , Sweden.

Ollig, A. (1995), ‘Entwicklung eines Verfahrens zur Differenzierung der

Kohlenstoffphasen im Koks und Einfl ussgr öß en auf die Ver ä nderungen der

Kohlenstoffphasen im Hochofen’, Dr.-Ing. Thesis RWTH Aachen.

Orth, A., Foerster, K., Weber, P. and Hietala, K. (2004), ‘Direct reduction of iron ore

fi nes applying the coal based Circofer ® process’, Proc. 2nd Int. Conference on New Developments in Metallurgical Process Technology , 6–8 June 2004, Riva

del Granda.

Parkash, S. (2010), Petroleum Fuels Manufacturing Handbook , McGraw-Hill, New

York.

Peters, M. and Luengen, H. B. (2009), ‘Iron making in western Europe’, Proc.5th Int. Congress on the Science and Technology of Ironmaking (ICSTI’09) , 20–22

October 2009, Shanghai, 22–28.

Peters, M. and Schmoele, P. (2012), ‘Koksqualitaet und Hochofenleistung’, Proc. 100 Jahre Kokereiausschuss des Stahlinstituts VDEh , 29–30 November 2012, 25

Jahre VDKF, Stahleisen GmbH, Duesseldorf, 79–89.

Peters, M., Schm ö le, P., Janhsen, U. and Wolny, H.-J. (2011), ‘Investigation of blast

furnace coke using optical particle analysis’, Proc. METEC InSteelCon ® 2011, 6th European Coke and Ironmaking Congress , D ü sseldorf, Germany (on

CD-ROM).

Prachethan Kumar, P., Barman, S. C., Reddy, B. M. and Sekhar, V. R. (2009), ‘Raw

materials for Corex and their infl uence on furnace performance’, Ironmaking and Steelmaking , 36 (2), 87–90.



Riley, M. F., Rosen, L. and Drnevich, R. (2010), ‘Mitigating CO 2 -emisssions in the

steel industry: a regional approach to a global need’, Iron and Steel Technology ,

February 2010.

Ruhrkohlen-Handbuch (1984), ‘Anhaltszahlen, Erfahrungswerte und praktische

Hinweise fuer industrielle Verbraucher’, Essen, 6th Edition, Verlag Glueckauf

GmbH, Essen.

Sahajwalla, V. and Gupta, S. (2005), ‘PCI coal combustion behaviour and residual

coal char carryover in the blast furnaces of three American steel companies

during pulverized coal injection (PCI) at high rates’. Final Report, prepared by

AISI, Washington DC.

Sha, Y. and Cao, J. (2011), ‘Technological improvements of ironmaking in China’,

Proc. METEC InSteelCon ® 2011, 6th European Coke and Ironmaking Congress, (ECIC) , 27 June–1 July 2011, D ü sseldorf, Germany (on CD-ROM).

Siebelhoff, H.-W. and Taylor, T. (2004), ‘Inbetriebnahme und erste Betriebserfahrungen

auf der neuen Kokerei Schwelgern’, Vortragsver ö ffentlichungen Kokereitechnik,

Essen, Germany.

Smoot, L. D., Eatough, S. R. and Miller, A. B. (2007), ‘Form coke reaction processes

in carbon dioxide’, Fuel , 86 , 2645–2649.

Stahl online (2011), Available from: http://www.stahl-online.de/Deutsch/Linke _

Navigation/Stahl_in_Zahlen/index.php?highmain=4&highsub=0&highsubsu

b=0) [Accessed September 2011].

Steel Institute VDEh (2008), ‘ Steel Manual ’, Stahleisen GmbH.

The International Standard ISO/CD 11323 (1999), Jahrbuch Stahl 2000, Band 1,

D ü sseldorf, Stahleisen GmbH.

Tsvik, G. (2011), ‘Impact of H2/CO ratio on syngas-based direct reduction shaft fur-

nace’, Proc. METEC InSteelCon ® 2011, 6th European Coke and Ironmaking

Congress (ECIC), D ü sseldorf, Germany, 27 June–1 July 2011 (on CD-ROM).

Ueda, S., Yanagiya, K., Watanabe, K., Murakami, T., Inoue, R. and Ariyama, T. (2009),

‘Reaction model and reduction behavior of carbon iron ore composite in blast

furnace’, ISIJ International , 49 (6), 827–836.

ULCOS (2011a), ‘Top gas recycling’, Available from: http://www.ulcos.org/en/

research/blast _furnace.php [Accessed 16 September 2011].

ULCOS (2011b), ‘HIsarna smelter technology’, Available from: http://www.ulcos.

org/en/research/isarna.php [Accessed 16 September 2011].

University of Tennessee, ‘Iron-carbon phase diagram (a review)’, Dept. of Materials

Science and Engineering, Available from: http://web.utk.edu/ ~prack/MSE%20

300/FeC.pdf [Accessed 6 September 2011].

Valia, H. S., ‘Coke production for blast furnace ironmaking’, Available from: http://

www.accci.org/Steel.pdf [Accessed 7 September 2011].

Von Bitter, R. W., Husain, R., Weber, P. and Eichberger, H. (1999), ‘Experiences

with two new fi ne ore reduction processes – Circored and Circofer,’ Proc. Int. Conference on New Developments in Metallurgical Process Technology , 13–15

June 1999, D ü sseldorf, 9–16.

Wang, S. (2004), ‘Verhalten von kohlenstoffhaltigen Eisenerzagglomeraten bei der

Reduktion’, Dr.-Ing. Thesis RWTH Aachen.

Wieder, K., B ö hm, C. and Wurm, J. (2004a), ‘The COREX ® and FINEX ® Processes –

Reliable, environmental friendly and economical Hot Metal Production’, VAI ,

12 pp.



Wieder, K., B ö hm, C., Wurm, J. and Vuletic, B. (2004b), ‘Confronting the coke short-

age with the COREX and FINEX Technology’, BHM , 149 (11), 379–384.

Wieder, K., B ö hm, C., Schmidt, U. and Grill, W. (2009), ‘COREX ® prepared for pre-

sent and future iron making challenges’, Proc. 5th Int. Congress on the Science and Technology of Ironmaking (ICSTI’09) , 20–22 October 2009, Shanghai,

1243–1249.

World steel association (2011), ‘Steel in fi gures’, Available from: http://www.world-

steel.org [Accessed 6 September 2011].

World Steel Dynamics (2011), ‘2010 world direct reduction statistics’, audited by

World Steel Dynamics, Available from: http://www.midrex.com/uploads/docu-

ments/MDX2010StatsBook.pdf [Accessed September 2011].

Wright, R., Kim, R. and Sch ü cker, F.-J. (2005), ‘Compacting of coal for heat recovery

ovens’, Proc. 5th European Coke and Ironmaking Congress , 12–15 June 2005,

Stockholm, Sweden, Tu 2:2-1/13.

Wu, S., Xu, J., Yagi, J., Guo, X. and Zhang, L. (2011), ‘Prediction of pre-reduction

shaft furnace with top gas recycling technology aiming to cut down CO 2 emis-

sion’, ISIJ International , 51 (8), 1344–1352.

Zhang, Q., Guo, L. and Chen, X. (2009), ‘Analysis of improving COREX-3000 com-

petence’, Proc. 5th Int. Congress on the Science and Technology of Ironmaking (ICSTI’09) , 20–22 October 2009, Shanghai, China, 1230–1232.

Zulhan, Z. (2006), ‘Der Einfl uss unterschiedlicher Kohlenstofftr ä ger auf die chaum-

schlackenbildung im Elektrolichtbogenofen’, Dr.-Ing. Thesis RWTH Aachen.

the coal handbook: towards cleaner production || coal use in iron and steel metallurgy

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